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man : Xprint(7)
Xprint(7) Xprint(7)
NAME
Xprint - The "X print service" - a portable, network-
transparent printing system based on the X11 protocol
SYNOPSIS
Xprint is a very flexible, extensible, scaleable,
client/server print system based on ISO 10175 (and some
other specs) and the X11 rendering protocol. Using Xprint
an application can search, query and use devices like
printers, FAX machines or create documents in formats like
PDF. In particular, an application can seek a printer,
query supported attributes (like paper size, trays, fonts
etc.), configure the printer device to match its needs and
print on it like on any other X device reusing parts of
the code which is used for the video card Xserver.
OVERVIEW
The "X Print Service" technology allows X rendering to
devices such as printers and fax. Most of the service is
available in the X11 technology stack as Xp, with the
remainder in single toolkit stacks (e.g. DtPrint for CDE).
Modifications have also been made to the LessTif/Motif/Qt
technology stacks to support Xprint.
The Xp portion consists of:
o Xp Extension for the X-Server (included in the X-Server
Xprt)
o Xp Extension API for the client side (libXp/libXprintU-
tils)
o PCL ddx driver that converts core X to native PCL
o PDF ddx driver that converts core X to native PDF
o PostScript ddx driver that converts core X to native
PostScript
o Raster ddx driver that generates xwd rasters which can
be converted to PCL, PDF or PostScript rasters
From an X clients perspective, it can attach to one of two
nearly identical X-Servers, a "Video" X-Server, and a
"Print" X-Server which has the additional Xp capability
but otherwise looks and behaves the same.
HOW THE X PRINT SERVICE WORKS
The X Print Service expands on the traditional X-Server
and Xlib world in four ways.
1. Most obvious is the use of "print ddx drivers" instead
of "video ddx drivers". While a video ddx driver
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modifies pixels in a video frame buffer, a print ddx
driver generates "page description language (PDL)"
output (such as PCL, PDF or PostScript) or sends the
print rendering instructions to a platform-specific
print API (like Win32/GDI).
Once a print ddx driver generates PDL output, it can
be sent to a spooler such as lp(1) or retrieved by the
client (to implement functionality like "print-to-
file").
Though not currently done, a single X-Server can sup-
port both print and video ddx drivers.
2. Since printers support "paged" output, unlike video, a
portion of the Xp Extension supports APIs to delineate
printed output. For example, XpStartPage and XpEnd-
Page tell the X-Server where a physical page starts
and ends in an otherwise continuous stream of X ren-
dering primitives. Likewise, XpStartJob and XpEndJob
determine when a collection of pages starts and ends.
XpEndJob typically causes the generated PDL to be sub-
mitted to a spooler, such as lp(1).
3. Since printers have extensive capabilities, another
portion of the Xp Extension supports APIs to manipu-
late "print contexts".
Once a printer is selected using the Xp Extension API,
a print context to represent it can be created. A
print context embodies the printer selected - it con-
tains the printer's default capabilities, selectable
range of capabilities, printer state, and generated
output. Some "attributes" within the print context can
be modified by the user, and the X-Server and print
ddx driver will react accordingly. For example, the
attribute "content-orientation" can be set to "land-
scape" or "portrait" (if the printer supports these
values - which can be queried using the Xprint API as
well).
4. Since printers can have "built in" fonts, the Xp
Extension in the X-Server works with the print ddx
drivers to make available (for printing only) addi-
tional fonts on a per print context basis.
When a print context is created and set for a given
printer, the X font calls may be able to access addi-
tional printer fonts. To do this (typically), the X-
Server must have access to "printer metric files"
(.pmf) that describe at minimum the metrics of the
built in fonts.
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USAGE
There are three tasks to start the X Print Service:
1. configuring the X Print Server,
2. starting the X Print Service
3. configuring the user session so that clients can find
the running X Print Service
The tasks are described in detail below.
SERVER CONFIGURATION
The X Print Server (Xprt) can read a number of configura-
tion files which control its behavior and support for
printers. Each vendor platform has a default location for
this information. Xprt can also read the environment vari-
able XPCONFIGDIR to locate alternate configuration direc-
tories. Common settings include:
export XPCONFIGDIR=/X11/lib/X11/XpConfig/
export XPCONFIGDIR=/proj/x11/xc/programs/Xserver/XpConfig/
Xprt has many built-in defaults, and lacking any configu-
ration files, will immediately try to support all printers
visible via lpstat(1).
In order of importance for configuration by a system
administrator, the configuration files for a "C" locale
are as follows (see Xprt(1) for more details (including
support for non-"C" locales)):
${XPCONFIGDIR}/C/print/Xprinters
'Xprinters' is the top most configuration file. It
tells Xprt which specific printer names (e.g.
mylaser) should be supported, and whether lpstat(1)
or other commands should be used to automatically
supplement the list of printers.
${XPCONFIGDIR}/C/print/attributes/printer
The 'printer' file maps printer names to model con-
figurations (see 'model-config' below). For exam-
ple, "mylaser" could be mapped to a "HPDJ1600C",
and all other arbitrary printers could be mapped to
a default, such as "HPLJ4SI". When depending on
lpstat(1) in the Xprinters file, setting up
defaults in 'printer' becomes all the more impor-
tant.
${XPCONFIGDIR}/C/print/attributes/document
The 'document' file specifies the initial document
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values for any print jobs. For example, which paper
tray to use, what default resolution, etc.
${XPCONFIGDIR}/C/print/attributes/job
The 'job' file specifies the initial job values for
any print jobs. For example, "notification-profile"
can be set so that when a print job is successfully
sent to a printer, e-mail is sent to the user.
${XPCONFIGDIR}/C/print/models/PSdefault/model-config,
${XPCON- FIGDIR}/C/print/models/PSdefault/fonts/fonts.dir,
${XPCON- FIGDIR}/C/print/models/PSde-
fault/fonts/9nb00051.pmf, ${XPCON-
FIGDIR}/C/print/models/PSdefault/fonts/9nb00093.pmf
The 'model-config' file has attributes that
describe the printer models capabilities and
default settings. Printer model fonts may also be
present. The model-config file also identifies the
print ddx driver to be used. For each printer
model supported, a complete hierarchy of files
should exist. In most cases, these files do not
need to be modified.
${XPCONFIGDIR}/C/print/ddx-config/raster/pcl,
${XPCON- FIGDIR}/C/print/ddx-config/raster/pdf,
${XPCON- FIGDIR}/C/print/ddx-config/raster/postscript
The print ddx drivers can have highly specific con-
figuration files to control their behavior. In most
cases, these files do not need to be modified.
More information in how to configure and customize the X
print server can be found in the Xprt(1) manual page.
STARTING UP
The summary checklist for starting the X Print Service is
as follows:
1. Choose an execution model for the X Print Service. The
X Print Service can be run on a per-user session
basis, per machine basis, or can be run on a few
machines globally available to a number of users.
2. If print jobs are to be submitted to a spooler (almost
always the case), make sure all needed printers are
available to the spooler subsystem (most often lp(1))
on the same machine running the X Print Service.
3. Configure the X Print Server. See ``X Print Server
Configuration''.
4. Depending on #1, start the X Print Server process
"Xprt", and then the toolkit-specific Print Dialog
Manager Daemon process (such as CDEnext's "dtpdmd") at
the appropriate times. Note that libXprintUtils-based
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applications/toolkits do not need a Print Dialog Man-
ager Daemon process to use Xprint.
The details are described below.
Because the X Print Service is based on X, it can be eas-
ily distributed. The most significant factors in which
execution model to choose will be driven by:
o how many printers will be accessable through the printer
subsystem on any given machine. A system administrator
may choose to cluster printers on a few given machines,
or scatter them across an organization and possibly make
extensive use of remote spoolers to make them globally
available.
o how many machines will need a copy of the X Print Server
configuration files. The files have been architected so
that one super-set version of them can be maintained and
distributed (e.g. via NFS), and a per-machine or per-
user version of the `Xprinters' is all that is needed to
have the appropriate information in them utilized or
ignored.
o how many users can demand services from a given X Print
Service.
With the above in mind, some obvious execution models
include:
o Global - in this model, the system administrator is
choosing to run the X Print Service on a *few* select
machines with appropriate printers configured, and allow
clients access to the global resource. This can central-
ize the administration of printers and configuration
files, but may have to be monitored for performance
loading.
Startup would likely be done by boot-up scripts (such as
/etc/init.d/xprint).
o Per-machine - every machine with potential X Print Ser-
vice users would run the service. Printer and configura-
tion file administration is decentralized, and usage
would be limited to the users on the machine.
Startup would likely be done by boot-up scripts (such as
/etc/init.d/xprint).
o Per-user session - every user would run an entire X
Print Service for themselves. In the future, the Video X
Server normally started may contain Print X Server capa-
bility, so this model becomes very natural.
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Startup would likely be done at session login or by
launching actions or processes manually once the user
logs in. Note: Deamons like "dtpdmd" must be started
after Xprt.
Starting of the processes is straight forward. In strict
order (example is for manually starting the X print server
for CDEnext usage):
1.
[machineA] % Xprt [-XpFile <Xprinters file>] [:dispNum] &
Note that Xprt will look for configuration files in
either a default location or where XPCONFIGDIR points.
-XpFile specifies an alternate `Xprinters' file,
rather than the default one or `${XPCON-
FIGDIR}/C/print/Xprinters'.
2.
[machineA] % dtpdmd -d machineA[:dispNum] [-l /tmp/dtpdmd.log] &
The dtpdmd will maintain an X-Selection on the X-
Server, and will start dtpdm's as required to service
requests.
In all but the per-user session model, the machine running
the dtpdmd (thus dtpdm's) will need display authorization
to the users video display.
CLIENT CONFIGURATION
Once a X Print Server and dtpdmd have been started -- many
of them in some cases -- clients will need to find and use
them. There are two mechanisms that allow clients to dis-
cover X Print Servers and printers.
o "X Print Specifier" - assuming usage of the
DtPrint/XprintUtils-based print applications, the fol-
lowing notation is understood:
printer_name@machine[:dispNum]
For example:
colorlj7@printhub:2
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In the above example, the X Print Server running at
`printhub:2' is assumed to support the printer named
`colorlj7'.
o ${XPSERVERLIST} - assuming usage of the DtPrint print
dialogs, the environment variable ${XPSERVERLIST} can
contain a list of X Print Servers. For example:
XPSERVERLIST="printhub:2 printhub:3 otherdept:0"
Then in the dialogs, only a printer name needs to be
entered. The dialog will then search the X Print
Servers in ${XPSERVERLIST} for a server than supports
the printer, and then establish contact.
END-USER SEQUENCE
From most CDEnext applications, printing is accomplished
by bringing down the <File> menu and selecting <Print...>.
This will result in the DtPrintSetupBox dialog, which will
request the name of a printer, and offer limited capabil-
ity to configure print options (e.g. number of copies). If
the user wishes, they can select <Setup...>, which will
start a dtpdm capable of modifying additional print
options. Finally, the user should select <Print>.
ENVIRONMENT
${XPCONFIGDIR}
This environment variable points to the root of the
Xprint server configuration directory hierarchy.
If the variable is not defined, the default path is
be assumed. The default path may be
/usr/X11R6/lib/X11/xserver/, /usr/lib/X11/xserver/,
/usr/share/Xprint/xserver/ or /usr/open-
win/server/etc/XpConfig, depending on the system,
and may be configured in /etc/init.d/xprint.
${LANG}
This environment variable selects the locale set-
tings used by the Xprint server. Xprt allows lan-
guage-specific settings (stored in ${XPCON-
FIGDIR}/${LANG}/print/) which will override the
default settings (stored in ${XPCON-
FIGDIR}/C/print/). If ${LANG} is not set "C" is
assumed.
${XPSERVERLIST}
The environment variable ${XPSERVERLIST} contains a
list of display identifiers (separated by whites-
pace) which tell an application where it can find
the Xprint servers. Usually ${XPSERVERLIST} is set
by the profile startup scripts (e.g. /etc/profile
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or /etc/profile.d/xprint.sh) using the output of
/etc/init.d/xprint get_xpserverlist.
Example:
export XPSERVERLIST="`/etc/init.d/xprint get_xpserverlist`"
Alternatively ${XPSERVERLIST} can be set manually.
Example:
export XPSERVERLIST="littlecat:80 bitdog:72"
instructs an application to find an Xprint server
at display 80 on the machine "littlecat" and at
display 72 on the machine bigdog.
${XPRINTER}
The environment variable ${XPRINTER} defines the
default printer used by print applications. The
syntax is either printername or printername@dis-
play.
Examples:
XPRINTER=ps003
tells an application to look for the first
printer named "ps003" on all Xprint servers.
XPRINTER=hplaser19@littlecat:80
tells an application to use the printer
"hplaser19" on the Xprint server at display
"littlecat:80".
If ${XPRINTER} is not set the applications will examine
the values of the ${PDPRINTER}, ${LPDEST}, and ${PRINTER}
environment variables (in that order).
SEE ALSO
X11(7), xplsprinters(1), xprehashprinterlist(1), xphel-
loworld(1), xpxmhelloworld(1), xpawhelloworld(1), xpxthel-
loworld(1), xpsimplehelloworld(1), Xserver(1), Xprt(1),
libXp(), libXprintUtils(), libXprintAppUtils(),
XmPrintShell(), XawPrintShell(), Xprint FAQ
(http://xprint.mozdev.org/docs/Xprint_FAQ.html), Xprint
main site (http://xprint.mozdev.org/)
AUTHORS
This manual page was written by Roland Mainz
<roland.mainzATnrubsig.org> based on the original X11R6.6
xc/programs/Xserver/XpConfig/README.
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